Chlorination of aromatic compounds

ABSTRACT

Nuclear chlorination of aromatic compounds having an electron donating group is effected by contacting said aromatic compound with copper (II) chloride in an aqueous hydrochloric acid solution and adding chlorine to the reaction system to maintain the mole ratio of (a) copper (I) chloride to (b) the sum of copper (I) chloride plus copper (II) chloride at more than 0.005/1 but less than about 0.3/1.

1 United States Patent [191 Nishihara et al.

[ 51 Oct. 28, 1975 [22] Filed: July 11, 1973 [21] Appl. No.: 378,217

[30] Foreign Application Priority Data Aug. 3, 1972 Japan 47-77975 Aug.3, 1972 Japan 47-77976 [52] US. Cl 260/575; 260/570.8 R; 260/5709;260/574; 260/576; 260/577; 260/578;

[51] Int. Cl. ..C07C 91/44; C07C 93/14; C07C 87/60 [58] Field of Search260/694, 578, 575

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 1,241,771 8/1971United Kingdom 260/578 OTHER PUBLICATIONS Clarens, Chem. Abstracts, Vol.16, p. 2440, (1922).

Cini et a]., Chem. Abstracts, Vol. 56, p. l4971c, (1962).

Primary ExaminerLewis Gotts Assistant ExaminerS. P. Williams Attorney,Agent, or Firm-Woodhams, Blanchard and Flynn [57] ABSTRACT Nuclearchlorination of aromatic compounds having an electron donating group iseffected by Contacting said aromatic compound with copper (II) chloridein an aqueous hydrochloric acid solution and adding chlorine to thereaction system to maintain the mole ratio of (a) copper (I) chloride to(b) the sum of copper (I) chloride plus copper (II) chloride at morethan 0.005/1 but less than about 0.3/1.

4 Claims, N0 Drawings CHLORINATION OF AROMATIC COMPOUNDS BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates tonuclear chlorination of aromatic compounds having an electron donatinggroup, particularly phenols and aromatic amines.

2. Description of the Prior Art The nuclear chlorination of aromaticcompounds having an electron donating group is known. For example, thechlorination of phenols by cupric chloride in hot aqueous hydrochloricacid is disclosed in Japanese Pat. Publication No. Sho 45-40882(40882/70), dated Dec. 22, 1970. The process disclosed in thispublication is advantageous in comparison with prior processes becausethe ratio of the desired para-substituted product to theortho-substituted product is increased and less severe reactionconditions are required.

Additional descriptions of this process and related processes are setforth in (l) H. P. Crocker and R. Walser, J. Chem. Soc. (c), 1970,1982-1986, (2) H. P. Crocker and R. Walser, Chem. and Ind., 1969,1141-1142, and (c) German Offen. 1800676, 1926852 and 2014773.

In the process of the above-referenced Japanese Patent Publication, foreconomic reasons, after the chlorination reaction is completed, thesolution of copper chlorides dissolved in aqueous hydrochloric acidsolution (hereinafter referred to as the working solution) is separatedfrom the organic products. The working solution is then oxidized with amolecular oxygencontaining gas and hydrogen chloride gas to convert thecuprous chloride therein to cupric chloride and the working solution isthen recycled for use in the next chlorination reaction. This is abatchwise recycling method. It is also proposed to carry out acontinuous method in which the chlorination of the aromatic compound andthe oxidation of cuprous chloride to cupric chloride are carriedsimultaneously by introducing hydrogen chloride gas and molecularoxygencontaining gas into the chlorination reaction solution.

There are some disadvantages in the abovementioned processes. In thecase of the abovementioned batchwise recycling method, the concentrationof cupric chloride in the chlorination reaction solution is reduced asthe chlorination reaction progresses and the rate of the chlorinationreaction falls remarkably. To keep the conversion of phenols at about80-90 percent, it is necessary to chlorinate for a long time or to use alarge excess of cupric chloride, such as 3-5 times the theoreticalamount. It is evident that such a method has numerous disadvantages,including increased cost of equipment because of the additional reactionvessel required for regenerating the working solution, increased cost ofcatalyst, reduction of the manufacturing capacity because of theadditional regeneration process, and the cost of expensive reaction andregeneration materials.

In the case of the continuous method, some advantages are achieved suchas lowering of the catalyst cost, shortening of the reaction timebecause of a higher reaction rate and obtaining a good conversion withless cupric chloride than is the case with the recycle method. But thecontinuous method does not avoid other disadvantages such as increasedcost of equipment and the use of expensive materials, and the need forexpensive safety precautions because of the use of oxygen gas andhydrogen chloride gas. In this continuous system, if the concentrationof hydrogen chloride is reduced, there is an increase of unwantedbyproducts and a reduction of the yield of the desired product, so thatthe introduction of hydrogen chloride gas is indispensable. Also, aircannot be used, in practice, as an oxygen source because much hydrogenchloride accompanies the unreacted gas (waste gas), and theconcentration of hydrogen chloride in the chlorination reaction liquiddecreases. The equipment and cost of recovering hydrogen chloride fromthe unreacted gas are substantial items of expense. It is necessary,therefore, to use oxygen gas for practical industrial operation of theprocess in order to reduce the volume of the unreacted gas.

In this prior art, the reaction of aniline is illustrated by thefollowing reaction equations.

201 c! 4l-IC1 0 4cuc1 +2H O (2) Therefore, it is required to use onemole of hydrogen chloride gas per one mole of aniline. An additionalquantity of hydrogen chloride gas is needed to maintain the requiredconcentration of hydrogen chloride in the water which is formed in thereaction. Furthermore, the chlorinated aniline is separated from thereaction system as the complex of cupric chloride and chlorinatedaniline hydrochloride. Therefore, it is necessary to use more than twomoles of hydrogen chloride gas per 1 mole of aniline.

Furthermore, in the prior art, the overall reaction rate is notsufficiently fast. The oxidation step of cuprous chloride to cupricchloride is the overall rate determining step, because of the very smallsolubility of oxygen gas in the reaction solution.

SUMMARY OF THE INVENTION We have discovered an economical chlorinationprocess capable of reducing the above-mentioned disadvantages. Ourprocess has high selectivity for the para-chloro-substitution product,and gives a high yield. In our process the chlorination of the aromaticcompound and the oxidation of cuprous chloride to cupric chloride areeffected at the same time by introducing chlorine gas into the reactionsolution containing cupric chloride, hydrogen chloride and the aromaticcompound. It is not required to use other oxidizing agents, such asoxygen gas.

It is an object of this invention economically to produce chlorinatedaromatic compounds which have electron donating group, such aschlorinated aromatic amines and chlorinated phenols, with higherselectivity to para-chloro-substitution products and a faster reactionrate.

The process of the present invention for preparing a chlorinatedaromatic compound consists essentially of reacting l an aromaticcompound having an electron donating group, preferably an aromaticcompound selected from the group consisting of aromatic amines andphenols, (2) aqueous hydrochloric acid (hydrogen chloride) and (3)cupric chloride, with the addition of (4) chlorine gas to the reactionmixture.

Preferably the rate of addition of chlorine gas is con- The aromaticamines used as starting materials for preparing the desired chlorinatedaromatic amine final products in the present invention have the formula(1):

ArNRR (I) wherein R and R represent members selected from the groupconsisting of hydrogen. alkyl having I to 12 carbon atoms and aralkylgroup having 7 to 12 carbon atoms. and R and R can be the same ordifferent; Ar represents a member selected from the group consisting ofphenyl and naphthyl, which can be unsubstituted or substituted byhydroxy, alkyl having 1 to 4 carbon atoms alkoxy having 1 to 6 carbonatoms or halogen, provided that Ar has at least one substitutablehydrogen at the 2. 4 or 6 positions relative to the -NRR group.

Preferred aromatic amines of the formula (1) are aniline, N-methylaniline, N,N-dimethyl aniline. o, m or p-anisidine, o-, m orp-phenetidine, o. m or pchloro aniline, o-phenylene diamine, 01- orB-naphthylamine, o-;, mor p-toluidine. o-, mor p-xylidine, pethylaniline, o-tertiary butyl aniline and 2,6-di-tertiary butyl aniline.Especially preferred aromatic amines of the formula (1) are the aromaticamines whose hydrochlorides are separable as a precipitate from reactionmixture, for example, o-toluidine, because the reaction product can beseparated easily. and the filtrate can be used for the next chlorinatingreaction with addition of more o-toluidine starting material.

The phenols used as starting materials for preparing the desiredchlorinated phenol final products in present invention have the formula(11):

wherein R represents a member selected from the group consisting of (a)hydrogen. (b) hydroxy, (c) halogen, (d) alkyl group having 1 to 4 carbonatoms which is either unsubstituted or substituted on the l to 5positions of the alkyl group by aryl, hydroxy aryl, mono-halogenatedhydroxy aryl, hydroxyl, carboxyl or their functional derivatives, and(e) aryl which is either unsubstituted or substituted by halogen, and/oralkyl group having 1 to 3 carbon atoms; R and R which can be the same ordifferent. represent a member selected 4 from the group consisting of(a) hydrogen, (b) alkyl having 1 to 4 carbon atoms which is eitherunsubstituted or substituted on the l to 5 positions of the alkyl groupby aryl. hydroxy aryl. mono-halogenated hydroxyl aryl, hydroxyl,carboxyl, or their functional derivatives, but when R is hydrogen, R andR can both be halogen atoms; and the phenol of formula (11) has at leastone substitutable hydrogen atom on the 2, 4 or 6 positions relative tothe hydroxy] group of the phenol. Preferred phenols of the formula (11)are phenol, o or p-phenyl phenol, o-chloro phenol, m-cresol, thymol,resorcinol. m-xylenol, p-chloro phenol and o-cresol.

The chlorination reaction temperature can vary depending on theparticular aromatic compound used as starting material, but generally atemperature of 70 to 150C, preferably 80 to 110C, is employed foraromatic amines, and a temperature of to C is employed for phenols.

It is preferred to use a high concentration of hydrogen chloride in thereaction mixture. In general the HCl concentration is 5 to 12 N,preferably 7 to 10 N, for aromatic amines, and generally theconcentration is more than 2 N, preferably more than 3 N, for phenols.

The mole ratio of cupric chloride plus cuprous chloride to aromaticstarting material is not critical, but this ratio preferably is in therange of 0.5 to 5:1 because the reaction is very slow and it isdifficult to control the chlorine gas feed rate when this ratio is toosmall.

Metal chlorides, in addition to cupric chloride, for example, LiCl,NaCl, MgCl CaCl- CdCl AlCl and FeCl can be present in the reactionmixture of the present invention, and some of them have an effect as anaccelerator of the reaction.

The reaction can be carried out at atmospheric pressure or at a pressureof l to 2 kg/cm (gauge pressure).

C upric chloride employed in the process of the present invention ismade present in the reaction system by adding thereto anhydrous cupricchloride, cupric chloride dihydrate, or a material which is converted tocupric chloride in hot aqueous hydrochloric acid, for example, cupricoxide, cupric sulfate, or cupric acetate or a material which isconverted to cupric chloride by chlorine in the reaction solution, forexample, cuprous oxide, cuprous chloride, or cuprous acetate.

The mole ratio of (a) cuprous chloride to (b) the sum of cuprouschloride and cupric chloride preferably is more than 0005/1 and, morepreferably is more than 0.02/1. The latter ratio of more than 0.02/1 isemployed to inhibit formation of tar and to permit substantial tolerancein the amount of chlorine introduced. But when a large amount of copperchlorides are present in reaction solution, that is, when the ratio of(b) the sum of cupric chloride and cuprous chloride to (c) the aromaticcompounds is very large, the mole ratio of (a) cuprous chloride to (b)the sum of cuprous chloride and cupric chloride can be kept at about0.005/ 1.

Furthermore, the mole ratio of (a) cuprous chloride to (b) the sum ofcuprous chloride and cupric chloride can be maintained as high as 0.2 to0.3, but the reaction rate is reduced in this range. Therefore, it ispreferred to maintain the mole ratio of (a)/(b) at about 0.02 to 0.15/1.0.

While a constant reaction rate can be obtained by maintaining constantthe mole ratio of (a) cuprous chloride to (b) the sum of cuprouschloride and cupric chloride, the present invention comprehendsintroducing chlorine intermittently, and allowing said mole ratio of(a)/(b) to vary within the stated limits.

Generally, in the chlorination of aromatic compounds having electrondonating group in aqueous hydrochloric acid, the ratio of para-chlorosubstituted product to ortho-chloro substituted product is 1-2/1. Thechlorination process cannot avoid the formation of considerable amountsof tar and high-boiling materials (dichloro substituted or trichlorosubstituted materials).

But, surprisingly, under the specially controlled conditions of thepresent invention, the ratio of parachloro substituted product to orthoproduct is very high as is shown in the following examples, and verysmall amounts of higher chlorinated products and tar are obtained.

The specially controlled conditions leading to this advantageous resultare obtained by introducing a suitable amount of chlorine gas into thereaction mixture to maintain the mole ratio of (a) cuprous chloride to(b) the sum of cuprous chloride plus cupric chloride at more than0.005/L0, more preferably at more than 0.02/ 1.0.

Under such condition. the chlorine taken in the reaction solution isimmediately preferentially consumed for effecting an oxidation reactionof cuprous chloride to cupric chloride. and the chlorination of thearomatic compound is effected essentially by the cupric chloride and thechlorine gas does not substantially react directly with the aromaticstarting material. Therefore the ratio of para-chloro substitutedproduct is very high, and the formation of higher chlorinated productsand tar is minimized.

In case there is supplied an excess amount of chlorine gas, i.e. morethan that required to maintain the mole ratio of (a)/(b) in theabove-stated range, the selectivity to the para product is reduced. andthe formation of tar increases.

The method of introducing chlorine gas into reaction solution can beselected suitably from known methods,

for example, bubbling pure or highly concentrated chlorine gas into thereaction solution by means of a gas introducing pipe or gas sparger.

Preferred methods of introducing chlorine gas into reaction solution areas follows; the first method is to introduce chlorine gas into the gasphase of the reaction vessel so that the chlorine gas is taken into thereaction solution from the surface of the reaction solu tion; the secondmethod is to introduce chlorine gas into the gas phase of the reactionvessel and the reaction solution is continuously recycled and gushedinto the gas phase and chlorine gas is thereby taken into the reactionsolution; the third method is to mix the chlorine gas outside thereaction vessel with the gases removed from the gas phase of thereaction vessel (preferably, this gas is an inert gas such as nitrogengas) and then bubbling this gas mixture into the reaction solution witha gas introducing pipe.

The amount of chlorine gas introduced into the reaction solution iscontrolled easily as follows: in the case of the first method, bycontrolling the speed of stirring of the reaction solution, the chlorinepartial pressure and the configuration of the baffle; in case of thesecond method, by controlling the chlorine partial pressure, the amountof recycled liquid and the style of the gushing method; in case of thethird method, by controlling the chlorine partial pressure, the amountof recycled gas, the speed of stirring and the type of bubbling methodemployed for bubbling the gas into the reaction solution.

The method of introducing chlorine to the reaction solution is notcritical, and for example, besides the above-mentioned preferredmethods, chlorine can be introduced into the reaction solution as anaqueous chlorine solution or liquefied chlorine can be bubbled into thesolution.

The method of the present invention is distinguished from the prior artmethods because no additional oxidizing agent, such as oxygen gas, needsto be added as is done in the abovementioned batchwise reaction andcontinuous reaction. However, the efi'ectiveness of the reaction is notharmed by the presence of a minor amount of oxygen gas in the reactionsystem.

LII

The reaction of the present invention is shown by the combination of thefollowing reaction equations in case of Z-methyl aniline.

Therefore, the net reaction is indicated as the following equations assum of the equations (4), (5). (6) and and cupric chloride may beconsidered to be a chemical catalyst.

The basic mode of the industrial practice of the present invention, inthe case of the starting material 2- methyl aniline as a preferredexample, is as follows: 4- chloro-2-methyl aniline hydrochloride whichis produced as an end product by the process of the present invention,precipitates in the reaction solution. and is filtered off at hottemperature. It is then washed with aqueous hydrochloric acid to removethe copper chlorides. The filtrate mixed withthe washings is mixed withfresh IZ-methyl aniline to form a reaction solution. Then chlorine isintroduced to the reaction solution. and the chlorination reaction iscarried out. Or alternatively. hydrochloric acid and a part of the watercan be distilled from the mixture of the filtrate and the washings, andthen to this distillate Z-methyl aniline is added, and then this mixtureis mixed with the reaction solution (i.e. the residue of the distilledmixture of the washings and the filtrate), and chlorination is thencarried out. In either case, theoretically, hydrochloric acid gas neednot be supplied to the reaction solution. although in practice make-uphydrochloric acid will normally be required.

Although the conversion of starting aromatic material to the chlorinatedend product can be kept at a low level, so that the withdrawn unreactedaromatic starting material can be recycled as a part of the raw startingmaterial of the next reaction, normally the conversion of the startingmaterial is easily maintained at a high level such as to percent. It isnot preferred to achieve conversions of 98 to 99 percent, because ofsolution. The oil liberated was collected and the aquethe possibilitiesof forming higher chlorinated materials ous layer was extracted withchloroform. The extract and tar. The process of the invention can becarried as together with the collected oil, were dehydrated and on abatchwise process, a semi-continuous process or a distillation underreduced pressure gave an oil (27.5 g) Continuous PI E and tar (0.05 g).The composition of this oil is shown The present invention provides animproved process below (by gas chromatography): for the chlorination ofaromatic compounds, which process has economical and industrialadvantages and achieves higher selectivity of the desired paraZ-methvlaniline 3.7971

Substltuted Product 10 (a-chlorb-Z-methyluniline 0.06%

In particular, the present invention provides an im-4-chloro-2-methylaniline 95.05?

proved process of chlormating aromatic compound, dchlom metmlm'lme 0107which process has many advantages compared with the above-mentionedprior art processes in which chlorination of the aromatic compound andoxidation of the cu- EXAMPLE 2 prous Chloride with Oxygen and f 9 gasThe apparatus described in Example 1 was used. A are carried outseparately. The reaction time is shortmixture of NNdimethy} aniline (02moles) and 223 ened because of the very high reaction rate, the total of22 9 wt ercent hydrochloric acid Solution was manufacturing time isshortened, the reaction process goured g flask and to this Solution 0 28moles is simpler, a higher reaction rate is achieved more rap- 2 Co er(H) chloride dih drate and 0 6 m 01 es of idly, the catalyst cost islower or a larger production cac0 i chloride were g The reac'tion wascap pacity is Obtained because the amount of Cupric chlorie l out at 90Cwith stirrin while introducin chloride employed can be reduced to lessthan the theoreti- I k cal amount (2 mole per 1 mole of aromatic comrmegas mto the 00sec apor space of the as i pound), and there is higherselectivity to the desired 0018. moles/hr for [0 hours' The amount of(ioppefl parasubstituted product. chloride was controlled to be between2.7 mo e percent Similarly, the present invention provides an imi 9percent throlighout the reaction i reproved process of chlorinationhaving many advantages acnon mixture was treated m t.he.same fashion asExample l, and 28.2 g of the distilled oil was obtained.

compared with the above-mentioned prior art process comprisingchlorination of aromatic compound and ox- 30 gg g yf the followmgComposltlon y g Chroma" idation of cuprous chloride with oxygen andhydrochloric acid gas simultaneously, such as the use of lower price rawmaterial (i.e. chlorine gas) as compared with anhydrous hydrochloricacid gas and oxygen, easier N,N-dimethyl aniline 8.92% n- 1 f h b r dcentration 6-chloro N,N-dimethyl aniline 0.01%

o y P because the con 4-chloro-N,N-dimethyl aniline 90.79% ofhydrochloric acid mcreases as the reaction pro-4764MmomNNdimethylaniline 1 gresses, and the shortening of the reactiontime because of the very high reaction rate.

The invention is further described in the following illustrativeexamples, which are not limiting.

' Into a flask as described in Example 1, 223 g of 22.9 EXAMPLE 1 wt.percent hydrochloric acid solution, 0.36 moles of Into a 500 ml flask,equipped with a thermometer, a copper (II) chloride, 0.04 moles ofcopper (I) chloride EXAMPLE 3 stirrer and a gas inlet tube, were added200 ml of 7 N- and 0.2 moles of aniline hydrochloride were intro-vhydrochloric acid solution, 0.28 moles of copper (II) duced. Withstirring, the reaction was carried out at 98 chloride dihydrate, 0.03moles of copper (I) chloride 100C for 15 hours, while chlorine gas wasintroand 0.2 moles of Z-methylaniline hydrochloride. After duced intothe vapor space of the flask at 0.0126 m0- replacing the air in thevapor space of the flask with niles/hr.

trogen gas, the stirred mixture was heated to 90C, then Th a t f o er(I) hloride was controlled bethe flask was closed and chlorine gas wasintroduced t e 59 le er ent and 8,3 mole ercent throughinto the closedvapor Space 05 e flask at a ram of out the reaction. The reactionmixture was treated in 0.0146 moles/hr for 13 hours, Whlle the Speed Ofthe the same fashion as Example 1, and 25.1 g of distilled stirrer waskept at 18 200 -poil was collected. This oil had the following composi-During the reaction, samples of the reaction mixture i b gaschromatography. were withdrawn periodically and the amount of copper (I)chloride based on the sum of copper (I) chloride and copper (II)chloride was measured iodometrically.

- Aniline 3.71% The results are shown in the following table. Lemmeaniline 0.05% 4-chloro aniline 95.84% 60 2.4-dichloro aniline 0.04%

Reaction time (hrs) 3 6 9 13 Amount of copper (l) 9.5 8.9 8.3 8.0chloride (mole 71) EXAMPLE 4 6 A mixture of 223 g of 22.9 wt. percenthydrochloric The resulting mixture was cooled to 40C and 0.25 acidsolution, 0.28 moles of copper (ll) chloride dihymoles of sodium sulfitewas added with mixing. Then drate, 0.03 moles of copper (I) chloride and0.2 moles the mixture was neutralized with an excess of ammonia ofp-anisidine were placed in a flask as described in Ex EXAMPLE Into aflask as described in Example 1, 223 g of 22.9 wt. percent hydrochloricacid solution, 0.28 moles of copper (ll) chloride dihydrate, 0.02 molesof copper (l) chloride and 0.2 moles of a-naphthylamine hydro chloridewere introduced. With stirring at l80-200 r.p.m., the reaction wascarried out at 95C for 6 hours, while chlorine gas was introduced intothe closed vapor space of the flask at 0.06 moles/hr.

The amount of copper (I) chloride was maintained between 6.7 and 5.1mole percent.

The stirred mixture was cooled and the solid was filu-naphthylamine2,4-dichloro-a-naphthylamine 4-chloro-a-naphthylamine EXAMPLE 6 Into a 2liter flask, equipped with a thermometer, a stirrer, a gas-inlet tubeand reflux condenser, 1,000 ml of 7 N-hydrochloric acid solution, 1.8moles of copper (ll) chloride dihydrate, 0.2 moles of copper (I)chloride and one mole of Z-methylaniline hydrochloride were introduced.After replacing the air in the vapor space of the flask with nitrogengas, at 90C, the gases in the space of the flask were started to recyclefrom the condenser to the reaction mixture through the gasinlet tube, byusing a gas circulating pump. The reaction was carried out at,90C for 8hours with stirring at 180-200 r.p.m., while the volume of thecirculating gas was kept at l/hr and chlorine gas was introduced intothe delivery tube of the pump at 0.12 moles/hr. The amount of copper (I)chloride was between 9.0 and 5.2 mole throughout the reaction.

The solid 4-chloro-2-methylaniline hydrochloride was filtered off whilethe mixture was still hot, and washed with a small amount of 7N-hydrochloric acid solution.

The solid was suspended in 350 g of water, and to this stirredsuspension sodium sulfite was added. After confirming that there were nocopper ([1) ions in this suspension, the resulting mixture wereneutralized with an excess of gaseous ammonia.

The liberated oil was extracted with chloroform, dried and distilledunder reduced pressure. A crude 4- chloro-Z-methylaniline oil (120.5 g)and tar (0.5 g)

were obtained. This oil had the following composition by gaschromatography.

Z-methylaniline 2.5'71

6-chloro-2-methylaniline 0.04% 4-chloro-2-methylaniline 97. 20%4.6-dichloro-Z-methylaniline 0.26%

Further, into the filtrate and washings, were added 0.9 moles ofZ-methylaniline hydrochloride and an amount of copper (ll)chloridedihydrate which corresponded to the amount of copper lost in thefiltration process. By using this solution, the second reaction(repeated reaction) was carried out for 8 hours under the sameconditions as described above. The amount of copper (l) chloride wasbetween 7.5 and 5.2 mole percent.

By following the same procedure of this example, distilled oil 130.1 g)and tar (0.47 g) were obtained. The composition of the oil is asfollows.

IZ-methylaniline 1.777: 6-chloro2-methyluniline 0.03%4-chloro-2-methylaniline 98. 10% 4.o-dichloro-2-methyluniline 0.10%

EXAMPLE 7 Into a 2 liter flask equipped with a thermometer, a stirrer, agas introducing tube and a reflux condenser, 1.000 ml of 7N-hydrochloric acid solution, 1.8 moles of copper (I1) chloridedihydrate, 0.2 moles of copper (I) chloride and one mole ofZ-methylaniline hydrochloride were added. With stirring at l200r.p.m.,the reaction was carried out at C for 9 hours, while chlorine gas waspassed into the reaction mixture at the rate of 0.1 moles/hr.

The waste gas from the condenser was washed with dilute caustic sodasolution. The amount of copper (l) chloride was between 6.3 and 4.7 molepercent throughout the reaction. By following the same procedure asExample 4, 4-chloro-2-methylaniline hydrochloride was separated,neutralized, extracted, dried and distilled under reduced pressure, acrude distilled oil (118.7 g) and tar (1.4 g) were obtained.

The composition of this oil is as follows.

Z-methylaniline 3.6%

G-chIoro-Z-methylaniline 0.03% 4-chloro-2-methylaniline 96.08% 4.6-dichloro-Z-methylaniline 0.29%

EXAMPLE 8 Into a 500 ml flask equipped with a thermometer, a stirrer anda gas-inlet tube, 200 ml of 6.5 N- hydrochloric acid solution, 0.28moles of copper (11) chloride, 0.03 moles of copper (l) chloride and 0.2moles of phenol were added. After replacing the air in the vapor spaceof the flask with nitrogen gas, the reaction was carried out at C for 13hours with stirring at -200 r.p.m., while chlorine gas was introducedReaction time (hrs) 3 6 9 Amount of copper (I) 7.9 chloride (mole 7:)

The resulting mixture was cooled and organic materials were extractedwith benzene. The extract was dried and distilled under reducedpressure. Distilled oil (24 g) was obtained and this had the followingcomposition by gas chromatography.

phenol 7.27r o-chlorophenol 7.67( p'chlorophcnol 81. 1'712.4-dichlorophe nol 4.1%

EXAMPLE 9 Into a flask as described in Example 8, 200 ml of 6.5N-hydrochloric acid solution. 0.28 moles of copper (II) chloride. 0.03moles of copper (I) chloride and 0.2 moles of m-xylenol were added. Withstirring, the reaction was carried out at 95C for 13 hours, whilechlorine gas was introduced into the closed vapor space of the flask at0.014 moles/hr. The ratio of copper (l) chloride was controlled between8.6 and 7.2 mole percent throughout the reaction. By following the sameprocedure as Example 8, distilled oil (28.2 g) was obtained and it hadthe following composition by gas chromatography.

m-xylenol 3.771 ochloro-m-xylenol 6.5% p-chloro-m-xylenol 88.5712.4-dichloro-mxylenol 1.371

EXAMPLE 10 The apparatus as described in Example 8 was used. Into theflask, 200 ml of 6 N-hydrochloric acid solution, 0.29 moles of copper(II) chloride dihydrate, 0.02

moles of copper (I) chloride and 0.2 moles of ochlorophenol were added.With stirring, the reaction was carried out at 9598C for 11 hours, whilechlorine gas was introduced into the closed vapor space of the flask at0.014 moles/hr.

The amount of copper (I) chloride was controlled between 6.3 and 4.6mole percent throughout the reaction.

By following the same procedure as described in Example 8, the distilledoil was found to contain 0- chlorophenol (25.2 percent),2,4-dichlorophenol (70.8 percent), 2,6-dichloropheno1 (3.1 percent) and2,4,6- trichlorophenol (0.9 percent).

The yield of 2,4-dichlorophenol was 94.7 percent based on the reactedo-chlorophenol.

EXAMPLE 1 1 Into a flask as described in Example 8, 200 ml of 6N-hydrochloric acid solution, 0.5 moles of copper (II) chloridedihydrate, 0.02 moles of Copper (1) chloride and 0.2 moles of o-cresolwere added. With stirring at 180-200 rpm, the reaction was carried outat 98C for 9 hours, while chlorine gas was introduced into the closedvapor space of the flask at 0.02 moles/hr. The amount of copper (I)chloride was controlled between 3.9 and 2.3 mole percent. By followingthe procedure of Example 8, the distilled oil was found to containo-cresol (8.8 percent), p-chIoro-o-cresol (87.4 percent),o-chloro-o-cresol (3.8 percent) and trace of dichloro-o-cresol by gaschromatography.

The yield of pchloro-o-cresol was 94.9 percent based on the reactedo-cresol.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A process for the nuclear chlorination of an aromatic amine of theformula ArNR R wherein R and R which are the same or different, arehydrogen, alkyl having one to 12 carbon atoms, or aralkyl having 7 to 12carbon atoms, and wherein Ar is phenyl, phenyl substituted by hydroxy,alkyl having 1 to 4 carbon atoms, alkoxy having one to 6 carbon atoms orhalogen naphthyl, naphthyl substituted by hydroxy, alkyl having I to 4carbon atoms, alkoxy having one to 6 carbon atoms or halogen providedthat said aromatic amine has at least one substitutable hydrogen at the2, 4 or 6 positions relative to NR R which comprises contacting in theliquid phase, reactants consisting essentially of A. said aromatic amineB. from 0.5 to 5.0 moles of copper (I) chloride plus copper (II)chloride, per mole of said aromatic amine, and

C. an aqueous solution of hydrochloric acid providing a concentration ofhydrochloric acid in the reaction system of from 5 to 12 N, at atemperature in the range of 70 to C, at a pressure in the range of fromatmospheric to about 2 kg/cm gauge, and adding to the reaction systemduring the progress of the reaction chlorine gas to convert copper (I)chloride to copper (II) chloride, the chlorine gas being supplied at arate effective to maintain the mole ratio of (a) copper (I) chloride/(b)copper (I) chloride plus copper (II) chloride, in the range of from0.005/1 to 0.15/1, throughout the entirety of the reaction, andrecovering the thus-formed chlorinated aromatic amine.

2. A process according to claim 1, in which the rate of addition ofchlorine gas to the reaction system is controlled to maintain the moleratio of (a) copper (I) chloride/ (b) copper (I) chloride plus copper(II) chloride in the range of from 0.02/1.0 to 0.l5/1.0 during theentirety of the reaction.

3. A process according to claim 1, in which the aromatic amine isselected from the group consisting of aniline, N-methyl aniline,N,N-dimethyl aniline, o, m-- or p-anisidine, o, m or p-phenetidine, o,mor p-chloro aniline, o-phenylene diamine, aor B-naphthylamine, o, morp-toluidine, o, m-or pxylidine, p-ethyl aniline, o-tertiary butylaniline and 2,6-di-tertiary butyl aniline.

4. A process according to claim 1, in which the aromatic amine isselected from the group consisting of 2- methyl aniline, N,N-dimethylaniline, aniline, p-

anisidine and a-naphthylamine.

1. A PROCESS FOR THE NUCLEAR CHLORINATION OF AN AROMATIC AMINE OF THEFORMULA
 2. A process according to claim 1, in which the rate of additionof chlorine gas to the reaction system is controlled to maintain themole ratio of (a) copper (I) chloride/(b) copper (I) chloride pluscopper (II) chloride in the range of from 0.02/1.0 to 0.15/1.0 duringthe entirety of the reaction.
 3. A process according to claim 1, inwhich the aromatic amine is selected from the group consisting ofaniline, N-methyl aniline, N,N-dimethyl aniline, o-, m- or p-anisidine,o-, m- or p-phenetidine, o-, m- or p-chloro aniline, o-phenylenediamine, Alpha - or Beta -naphthylamine, o-, m- or p-toluidine, om- orp-xylidine, p-ethyl aniline, o-tertiary butyl aniline and2,6-di-tertiary butyl aniline.
 4. A process according to claim 1, inwhich the aromatic amine is selected from the group consisting of2-methyl aniline, N,N-dimethyl aniline, aniline, p-anisidine and Alpha-naphthylamine.